This invention generally relates to a magnetoresistance head for use in a magnetic disk drive and to a method of fabricating the same.
Recently, with the increase of the capacity of a magnetic disk drive used as an external storage device for a computer, there is a demand for a high-performance magnetic head. A magnetoresistance head (MR head), which allows high-level output to be obtained irrespective of the speed at which the recording medium is run, is recognized as being capable of meeting such a requirement.
FIGS. 1A and 1B show a conventional MR head; FIG. 1A is a top view; and FIG. 1B is a cross sectional view. In the figures, a rectangular magnetoresistance element (MR element) 31 is connected to the ends of a pair of lead conductor layers 32. The MR element 31 and the lead conductor layers 32 are sandwiched by non-magnetic insulating layers 34a and 34b. The non-magnetic insulating layers 34a and 34b are sandwiched by an upper shield 33a and a lower shield 33b provided for magnetic shielding.
A sensing current j is allowed to flow through the lead conductor layers 32 and the MR element 31, to be fed to a signal detection area 36, in the MR element 31, defined by the lead conductor layers 32. The magnetic recording medium 37 is moved in the x-axis direction below the head so that the MR head can detect magnetic variations in the medium 37 as the variations in the electrical resistance of the signal detection area 36.
The upper shield 33a serves as a lower magnetic pole on which to provide a recording gap 38 formed of Al.sub.2 O.sub.3. On top of the recording gap 38, there are formed an inter-layer insulating layer 39 made of thermosetting plastic, a thin-film Cu coil 40 and a magnetic pole 41 made of NiFe alloy film, in the stated order, so as to form a recording head.
As shown in FIG. 2A, the conventional MR head is constructed such that the lead conductor layers 32 formed on the MR element 31 become gradually thinner near the signal detection area 36. Therefore, there is a problem in that the resistance of the signal detection area 36 varies toward the ends thereof with the result that the signal detection area 36 is poorly defined.
There is also proposed an arrangement shown in FIG. 2B, adapted to improve the precision with which the signal detection area 36 is defined, wherein a non-magnetic insulating layer 34c is provided so as to be contiguous with the non-magnetic insulating area 34a so that the signal detection area 36 is defined with a distance d, which is the distance between two directly opposite points at which the MR element 31 is in contact with the lead conductor layers 32. However, this arrangement also has a problem in that irregularity in the linearity of the recording gap 38, provided between the upper shield 33a and the upper magnetic pole 41, is created over the distance d of the signal detection area 36, with the result that a poor frequency characteristic of the head is produced especially in the high-frequency range.
It is therefore an object of the present invention to provide an improved magnetoresistance head and a method of fabricating the same by which head and method the signal detection area of a magnetoresistance element is more precisely defined, and deterioration in the frequency characteristic is prevented.